Myeloproliferative neoplasms (MPN) are diseases that are characterized by overproduction of mature blood cells. These diseases are commonly characterized by somatic activating mutations in the Janus Kinase 2 (JAK2) pathway, including mutations in the JAK2 protein itself (JAK2V617F) or in the coexpressed thrombopoietin receptor MPLW515L/K. The most feared complication of MPN is the transformation to acute myeloid leukemia (AML) - patients with leukemic progression show a median survival of less than six months and ultimate mortality of 98%. Conventional anti-leukemic therapies have demonstrated little efficacy in patients with MPN who develop AML, and no therapy has been demonstrated beyond supportive care for these patients, indicating a powerful need for new models and improved approaches toward therapy of this disease. Because patients with MPN usually present to the clinic before they progress to leukemia, samples from patients taken before and after progression allow us to dissect the sequence of genomic and epigenomic events that are associated with leukemic transformation. In patient samples, mutations in the isocitrate dehydrogenase (IDH) and TET2 proteins, which are functionally related epigenetic effectors, have been associated with this transformation and significantly reduced leukemia-free survival. To date, no models of transformation from MPN to AML have been developed, and there are no published data investigating leukemic cooperativity between JAK2 and IDH mutations in vivo. In order to advance our understanding of the sequential events in leukemogenesis and improve therapeutic options for Post-MPN AML patients, we will explore this process through three approaches. Human samples of paired chronic phase and post-MPN AML samples will be examined using genetic and epigenetic studies to assess the impact of specific mutations on leukemic transformation. In vitro models, including cell lines and primary bone marrow cells, will be used to assess the epigenetic and signaling aberrations that occur at the time of transformation. Finally, a mouse model of leukemic transformation will be generated by expressing JAK2V617F and IDH mutations in a temporal and spatially controlled manner. This model will be subsequently used to assess the efficacy of JAK-STAT and IDH inhibitors, alone and in combination, to determine if targeting multiple oncogenic disease alleles results in increased drug efficacy. The approaches in this proposal provide platforms to train an aspiring MD-PhD scientist in translational biology using clinical genomics and biological models.